(LEAD) S. Korea, U.S. to resume talks soon on revision of nuclear accord

SEOUL, April 1 (Yonhap) -- South Korea and the United States are poised to resume sensitive negotiations soon aimed at revising a bilateral civilian nuclear accord, a diplomatic source said Monday, as Seoul seeks to enrich uranium and reprocess spent nuclear fuel.

The allies are likely to reopen the talks as early as this week in Washington, when South Korean Foreign Minister Yun Byung-se visits there for a bilateral meeting with U.S. Secretary of State John Kerry, the source said on the condition of anonymity.

"Korea and the U.S. will soon resume the formal negotiations," the source said. If resumed, it will mark the sixth round of talks.

Yun is set to leave for Washington later Monday for a three-day visit. On Tuesday (Washington time), Yun will hold his first bilateral talks with Kerry.

The talks between Yun and Kerry will also focus on North Korea and other bilateral issues in the run-up to a U.S. visit by President Park Geun-hye in May.

Yun's trip was deemed unusual as Kerry plans to visit Seoul this month, meaning they will have two separate meetings in as many weeks.

South Korea's chief nuclear envoy, Lim Sung-nam, will accompany Yun during this week's trip to Washington. Lim will hold a separate meeting with Glyn Davies, U.S. special representative for North Korea policy, ministry officials said.

Revising the civilian nuclear agreement, which expires next year, is a key pending bilateral agenda for President Park and the second-term administration of U.S. President Barack Obama.

Little progress has been made in bilateral talks since 2010 to revise the 1974 accord that bans South Korea from enriching uranium and reprocessing spent nuclear fuel.

For a revised accord to be approved by the U.S. Congress, both sides must conclude negotiations by June of this year, ministry officials said.

Last week, Park asked for U.S. congressional support for South Korea to expand its "peaceful use" of atomic energy.

Park made the remark when she met with U.S. Sen. Bob Corker, the top Republican on the Senate Foreign Relations Committee, saying she hopes the expiring nuclear accord between the two countries will be revised in an advanced way, according to spokeswoman Kim Haing.

South Korea, a major nuclear energy developer, wants the U.S. to allow it to adopt proliferation-resistant technology for enriching uranium and reprocessing spent atomic fuel from its 22 nuclear power plants, but Washington has been reluctant to do so.

In the face of growing nuclear waste stockpiles and its ambition to become a global power in the civilian nuclear industry, South Korea hopes to adopt the so-called pyroprocessing technology, which leaves separated plutonium, the main ingredient in making atomic bombs, mixed with other elements.

South Korea wants the U.S. to allow it to use the new technology because it has to deal with more than 10,000 tons of nuclear waste at storage facilities that are expected to reach capacity by 2016.

Some nonproliferation experts say pyroprocessing is not significantly different from reprocessing, and the plutonium could be quickly turned into weapons-grade material.